Individuals or organizations may have one or more items that they would like to offer for sale. In some cases, these items are high value and/or one of a kind items, such as real estate. These items may be listed on various websites that list items for sale. Over time, information about the item may change (e.g., the price may drop if the item does not sell in a given period), but not all of the websites may contain the latest data. As a result, there is a need for improvement in handling listing data associated with multiple disparate data sources.